The present invention relates to an electric machine, in particular a synchronous machine.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
In general, an electric machine has a primary part with teeth, which are each surrounded by a coil, and a secondary part with teeth, which has a means for guiding a magnetic field. In addition to the coil, at least one permanent magnet is provided in each tooth unit. Such an electric machine is described, for example, in the article “A Novel High-Torque Reluctance Motor with Rare-Earth Magnet” by N. Iwabuchi et al. in IEEE Transactions on Industry Applications 30(1994), May/June, No. 3, New York, US, pages 609 to 613. As disclosed in this article, the permanent magnets are each fitted at the end region of the teeth, the polarity of the magnets alternating within a tooth and also when bridging the teeth from permanent magnet to permanent magnet.
U.S. patent application Publ. No. 2003/0122440 A1, published July 3, describes a disposition of the permanent magnets within a tooth. For example, one permanent magnet is arranged in a tooth in an end region thereof. An alternative involves the arrangement of a skewed permanent magnet in every second tooth of the primary part.
U.S. Reissued Pat. No. RE37,027 E describes a primary part having two coils and two permanent magnets at different points.
It would therefore be desirable and advantageous to provide an improved electric machine which obviates prior art shortcomings and which is simple in construction. Such a simplified construction is desirable in particular in the case of a synchronous machine, for example, a permanently excited synchronous machine or a separately excited synchronous machine.